CN112174511A - Sintering device for loose body of optical fiber preform rod and application method thereof - Google Patents
Sintering device for loose body of optical fiber preform rod and application method thereof Download PDFInfo
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- CN112174511A CN112174511A CN202011156135.9A CN202011156135A CN112174511A CN 112174511 A CN112174511 A CN 112174511A CN 202011156135 A CN202011156135 A CN 202011156135A CN 112174511 A CN112174511 A CN 112174511A
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
- C03B37/01446—Thermal after-treatment of preforms, e.g. dehydrating, consolidating, sintering
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
- Y02P40/57—Improving the yield, e-g- reduction of reject rates
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Abstract
The invention provides a sintering device for a loose body of an optical fiber preform rod; comprises a lifting device, a telescopic platform, a rotating device, a guide rod, a furnace core pipe, a flow guide sleeve and a heater; the guide rod is connected with the flow guide sleeve, a loose body is arranged below the flow guide sleeve, and the necking region of the loose body is completely covered in the flow guide sleeve; the furnace core pipe is arranged below the guide rod, and a heater is arranged outside the furnace core pipe; the flow guide sleeve comprises a conical cylinder and a cylindrical base which are distributed up and down, the process gas can be covered in the necking region of the loose body, and the surface of the conical cylinder is provided with a plurality of hollow small holes; the invention also provides an application method of the sintering device for the loose body of the optical fiber preform rod. The invention completely covers the process dehydroxylation gas in the necking area of the loose body of the optical fiber perform rod by means of the conical guide sleeve, ensures the chlorine concentration partial pressure in the necking area, improves the dehydroxylation effect of the necking area, improves the product quality of the optical fiber and effectively reduces the manufacturing cost of the optical fiber perform rod.
Description
The technical field is as follows:
the invention belongs to the technical field of optical fiber perform manufacturing, and particularly relates to a sintering device for a loose body of an optical fiber perform and an application method thereof.
Background art:
at present, the domestic optical fiber market is unstable, the unit price of optical fibers is reduced year after year, and the profit margin of each large optical fiber enterprise is greatly compressed, so that the enterprise can only make up the loss by compressing the manufacturing cost of optical fiber raw materials, namely optical fiber preforms layer by layer. The most effective means for reducing the production cost is to improve the qualification rate of the prefabricated rod and reduce the rejection rate of semi-finished products in the production process.
In the existing optical fiber preform preparation process, a core rod is mostly produced by adopting an axial vapor deposition method (VAD), and an outer cladding layer is produced by adopting an outer vapor deposition method (OVD) to produce the optical fiber preform by a two-step method. The VAD process is usually used for preparing a core rod of an optical fiber preform, the process control of the core rod directly influences various optical parameter indexes of the optical fiber preform after drawing, wherein the preparation of the low water peak optical fiber can be realized in the dehydroxylation stage in the sintering process of a loose body of the core rod, and the transparency of the loose body is realized in the glass densification stage in the sintering process. However, in the conventional sintering technology, the mixture of chlorine and helium as dehydroxylation process gases is introduced from the bottom of the furnace core tube and exhausted by pumping from the top. Because the molecular mass of chlorine is 71g/mol and is far higher than that of other auxiliary gases, the chlorine is easy to be enriched at the middle-lower part of the furnace core pipe, in addition, the gap between the necking zone at the top of the loose body and the pipe wall of the furnace core pipe exceeds the gap between other parts of the loose body and the pipe wall of the furnace core pipe, the concentration and partial pressure of the chlorine at the top of the loose body, especially the necking zone, is reduced, the dehydroxylation reaction (such as a reaction formula 1) degree is lower, and the removal effect of hydroxyl and water molecules at the initial section of the loose body is poorer than that at other parts after sintering: the hydroxyl content in the necking region of the optical fiber preform is too high, and the water peak (1383nm attenuation coefficient) of the G.652D optical fiber after drawing is enlarged, so that the proportion of the degraded optical fiber G.652B optical fiber (1383nm attenuation coefficient >0.355dB/km) is increased. Currently, enterprises only guarantee the attenuation level of the optical fiber by cutting the area with larger attenuation, which increases the production cost. On the other hand: the chlorine concentration partial pressure at the top of the loose body, particularly in a necking area, is reduced, the uniformity of axial optical parameters of the prefabricated rod, such as the core package relative refractive index difference value, is also reduced, the core package relative refractive index difference value is large and small, the optical fiber Mode Field Diameter (MFD) coefficient exceeds the standard, and finally the quality of an optical fiber product is reduced.
Chinese patent CN207435310 discloses a sintering device for a large-size loose powder rod for optical fibers, which is used for preparing a low-water-peak optical fiber preform by arranging a flow guide cover with a top necking below the loose powder rod in a furnace core pipe to increase the contact between the loose powder and dehydroxylation gas, but the following problems can be caused in the actual use process of directly placing the flow guide cover in the furnace core pipe in the patent: 1. the top necking size of the middle air guide sleeve in the furnace core tube is shaped for one time, and only loose powder sticks with the outer diameter smaller than the necking size can be sintered in a matching way; 2. if the loose powder rod in the sintering process falls due to cracking, the diversion cover at the bottom of the furnace core pipe can be directly smashed, and meanwhile, due to the limitation of the diversion cover, the cleaning of the bottom of the furnace core pipe can be troublesome, and the equipment cannot be continuously used.
Therefore, in order to reduce or avoid the cutting of the attenuation unqualified part in the necking region of the loose body of the optical fiber preform and improve the uniformity of the axial relative refractive index of the preform, a sintering device and a sintering method for ensuring the chlorine concentration partial pressure in the dehydroxylation stage of the loose body of the optical fiber preform are urgently needed.
The invention content is as follows:
the invention aims to provide a sintering device of an optical fiber preform loose body and an application method thereof, aiming at the defects of the prior art.
The invention adopts the following technical scheme:
a sintering device for loose bodies of optical fiber preforms comprises a lifting device, a guide rod, a furnace core pipe, a flow guide sleeve and a heater; the guide rod is connected with the lifting device on one hand and is connected with the flow guide sleeve on the other hand, a loose body is arranged below the flow guide sleeve, and the necking region of the loose body is completely covered in the flow guide sleeve; the furnace core pipe is arranged below the guide rod, and a heater is arranged outside the furnace core pipe; the lifting device can drive the guide rod and the flow guide sleeve to move up and down so as to drive the loose body to move up and down, thereby realizing the process that the loose body enters the furnace core tube for sintering and leaves the furnace core tube after sintering; the flow guide sleeve comprises a conical cylinder and a cylindrical base which are distributed up and down, and process gases (chlorine and helium) can be covered in a necking area of the loose body so as to increase the dehydroxylation effect of the necking area; the surface of the conical cylinder is provided with a plurality of hollow small holes for exhausting.
Further, the lifting device comprises a tower guide rail and a first lifting platform which are vertically arranged, and the guide rod is connected with the first lifting platform; the first lifting platform can move up and down along the tower guide rail, and then drives the guide rod to move up and down.
Furthermore, a rotating device is further arranged on the first lifting platform, and the guide rod is connected with the rotating device; the guide rod can be driven by the rotating device to rotate horizontally.
Further, the device also comprises a second lifting platform and a telescopic platform; the second lifting platform is arranged on the tower guide rail and can move up and down along the tower guide rail, and the second lifting platform is positioned below the first lifting platform; the telescopic platform is used for supporting the flow guide sleeve, is arranged on the second lifting platform and comprises a base, a telescopic piece and a fixed flat plate; the base is fixed on the second lifting platform and is sequentially connected with the telescopic piece and the fixed flat plate; the fixed flat plate is horizontally arranged and can move vertically or horizontally under the driving of the second lifting platform or the telescopic piece.
Furthermore, the guide rod is detachably connected with the guide sleeve, a guide rod bolt hole is formed in the guide rod, a guide sleeve bolt hole is formed in the guide sleeve, and after the guide rod bolt hole is aligned with the guide sleeve bolt hole, a quartz bolt is simultaneously inserted into the guide rod bolt hole and fixed with the guide sleeve bolt hole.
Furthermore, the loose body is detachably connected to the lower end of the guide rod through a conversion structure, the conversion structure comprises a quartz adapter cylinder and a quartz target rod, the quartz adapter cylinder is connected with the lower end of the guide rod, the quartz target rod is fixed below the quartz adapter cylinder, and the quartz target rod is fixedly connected with the loose body; the quartz adapter cylinder is provided with a pin hole, correspondingly, the lower end of the guide rod is provided with a pin hole corresponding to the guide rod, and the quartz adapter cylinder is fixedly connected with the guide rod through the pin hole and the bolt.
Furthermore, the heater is a graphite heater and is annularly distributed outside the furnace core pipe; and a graphite heat preservation felt is arranged outside the heater in an annular mode.
Further, the bottom of the furnace core pipe is provided with an air inlet, and the top of the furnace core pipe is provided with an air outlet; and a first air seal ring and a second air seal ring are arranged at the air outlet.
Further, the material of the flow guide sleeve is GE-214 high-purity quartz; the fixed flat plate is made of Teflon.
Furthermore, the extensible member is a metal extensible framework, and an adjusting knob is arranged on the metal extensible framework and used for adjusting the extension.
The application method of the sintering device for the loose body of the optical fiber preform comprises the following steps:
s1, mounting of the guide rod and the loose body:
the second lifting platform and the telescopic piece are controlled to move the fixed flat plate right above the furnace core pipe, so that the fixed flat plate is supported below the flow guide sleeve; operating the second lifting platform until the distance between the base of the guide sleeve and the pipe orifice of the furnace core pipe is L1; operating the first lifting platform to enable the guide rod to extend into the flow guide sleeve, and fixedly connecting the loose body to the lower end of the guide rod;
s2, mounting of the guide rod and the flow guide sleeve:
controlling the second lifting platform, and reducing the height of the telescopic platform until the distance L2 between the base of the flow guide sleeve and the pipe orifice of the furnace core pipe; moving the guide rod until the guide rod bolt hole is aligned with the guide sleeve bolt hole, and inserting and fixing a quartz bolt into the guide rod bolt hole and the guide sleeve bolt hole simultaneously to realize the fixed connection of the guide rod and the guide sleeve; then, the second lifting platform and the telescopic piece are controlled to enable the fixed flat plate to be withdrawn from the operation area;
s3, feeding the loose body into a sintering area:
controlling the first lifting platform to enable the guide rod to descend until the bottom of the loose body enters a high-temperature area of the furnace core pipe (namely the top end position of the graphite heater), and simultaneously sequentially covering the top of the furnace core pipe by the first air-seal ring and the second air-seal ring respectively;
s4, starting sintering:
firstly, dehydroxylating the loose body, raising the temperature in the furnace core pipe to 900-; stopping chlorine gas intake after the dehydroxylation process is finished, and automatically lifting the loose body to the top position of the heater; continuously raising the temperature in the furnace core tube to 1500 ℃, and slowly lowering the loose body to carry out glass transparentization; stopping helium gas inlet and the guide rod from rotating after the loose body is completely vitrified; the temperature in the furnace core pipe is reduced to 800-;
s5, separating the guide rod from the flow guide sleeve:
after the flow guide sleeve is cooled to the room temperature, the second lifting platform and the telescopic piece are regulated and controlled, so that the fixed flat plate moves to the position below the flow guide sleeve and supports the flow guide sleeve; pulling off the quartz bolt;
s6 unloading and sintering mother rod
After the guide rod is separated from the guide sleeve, the guide rod is controlled to descend, and the sintering mother rod is unloaded;
and S7, cleaning the guide sleeve.
Furthermore, the distance between the bottom of the guide sleeve and the nozzle of the furnace core pipe is L1: 2000-2300 mm, and the distance between the bottom of the guide sleeve and the nozzle of the furnace core pipe is L2: 1800-2000 mm.
Furthermore, in the dehydroxylation process of the loose body, after chlorine and helium are introduced from the bottom of the furnace core pipe, the neck area at the upper end of the loose body is completely covered by the guide sleeve base, so that the concentration of the chlorine entering the inside of the guide sleeve can be ensured, the neck area of the loose body is fully reacted with the chlorine, and the generated waste gas, namely hydrogen chloride and redundant chlorine can be discharged from the small hollow holes of the guide sleeve, and finally discharged out of the furnace core pipe.
The invention has the beneficial effects that:
(1) the invention completely covers the process dehydroxylation gas in the necking area of the loose body of the optical fiber preform rod by means of the conical guide sleeve, ensures the chlorine concentration partial pressure of the necking area, and improves the dehydroxylation effect of the necking area, thereby reducing the optical fiber 'water peak' after drawing in the necking area of the optical fiber preform rod on one hand, improving the uniformity of the axial relative refractive index of the optical fiber preform rod on the other hand, finally improving the product quality of the optical fiber and effectively reducing the manufacturing cost of the optical fiber preform rod;
(2) by arranging the lifting device and the telescopic platform, the loose body can be conveniently installed and the sintering mother rod can be conveniently unloaded in the loose body sintering preparation and sintering finishing processes; the invention has reasonable design, simple structure and convenient operation, can greatly improve the production efficiency and the product quality, and has strong practicability and wide applicability.
Description of the drawings:
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a schematic view of the loose structure of an optical fiber preform according to the present invention;
FIG. 3 is a schematic perspective view of a flow sleeve according to an embodiment of the present invention;
FIG. 4 is a cross-sectional view of a flow sleeve according to an embodiment of the present invention;
FIG. 5 is a top view of a flow sleeve according to an embodiment of the present invention;
FIG. 6 is a schematic structural diagram of a retractable platform according to an embodiment of the present invention;
FIG. 7 is a schematic diagram illustrating the operation of the guide sleeve during the lifting operation according to the embodiment of the present invention;
FIG. 8 is a schematic view of the operation of installing the loose body in the embodiment of the present invention;
FIG. 9 is a schematic view showing the completion of sintering of the porous body in the embodiment of the present invention;
FIG. 10 is a graph showing the 1310nm, 1383nm and 1550nm attenuation profiles of optical fibers after sintering a bulk by a conventional method;
FIGS. 11 and 12 are graphs of attenuation profiles of optical fibers 1310, 1383, 1550nm according to embodiments of the present invention;
FIG. 13 is a graph of the relative refractive index difference of an axial core of an optical fiber preform according to an embodiment of the present invention;
FIG. 14 is an MFD distribution plot of optical fibers at 1310nm and 1550nm according to an embodiment of the present invention;
the labels in the figures are: 1. a tower rail; 2. a first lifting platform; 3. a rotating device; 4. a guide rod; 5. a second lifting platform; 6. a telescopic platform; 7. a flow sleeve; 7-1, a conical cylinder; 7-2, a cylindrical base; 8. a quartz bolt; 9. a quartz adapter cylinder; 10. a quartz target rod; 11. a loose body; 12. a furnace core pipe; 13. a first airtight ring; 14. a second gas seal ring; 15. a heater; 16. graphite insulation felt; 17. a flow guide sleeve bolt hole; 18. hollowing out small holes; 19. a base; 20. adjusting a knob; 21. a metal telescopic framework; 22. fixing the flat plate; 23. a pin hole of the guide rod; 24. sintering the mother rod; 25. a neck-reducing region.
The specific implementation mode is as follows:
in order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
Referring to fig. 1 to 9, an embodiment of the present invention provides a sintering apparatus for an optical fiber preform loose body, including a lifting device, a guide rod 4, a furnace core tube 12, a flow guide sleeve 7, and a heater 15; the guide rod 4 is connected with the lifting device on one hand and the flow guide sleeve 7 on the other hand, a loose body 11 is arranged below the flow guide sleeve 7, and a necking region 25 of the loose body 11 is completely covered in the flow guide sleeve 7; the furnace core pipe 12 is arranged below the guide rod 4, and a heater 15 is arranged outside the furnace core pipe 12; the lifting device can drive the guide rod 4 and the flow guide sleeve 7 to move up and down, so as to drive the loose body 11 to move up and down, thereby realizing the process that the loose body 11 enters the furnace core pipe 12 to be sintered and leaves the furnace core pipe 12 after the sintering is finished; the flow guide sleeve 7 comprises a conical cylinder 7-1 and a cylindrical base 7-2 which are distributed up and down, and process gases (chlorine and helium) can be covered in a necking area 25 of the loose body 11 so as to increase the dehydroxylation effect of the necking area 25; the surface of the conical cylinder 7-1 is provided with a plurality of hollowed-out small holes 18 for exhausting; the heater 15 is a graphite heater and is annularly distributed outside the furnace core pipe 12; a graphite heat preservation felt 16 is arranged outside the heater 15.
In the embodiment of the invention, the lifting device comprises a tower guide rail 1 and a first lifting platform 2 which are vertically arranged, and the guide rod 4 is connected with the first lifting platform 2; the first lifting platform 2 can move up and down along the tower guide rail 1, and further drives the guide rod 4 to move up and down; the first lifting platform 2 is also provided with a rotating device 3, and a guide rod 4 is connected with the rotating device 3; the guide rod 4 can be driven by the rotating device 3 to rotate horizontally.
In the embodiment of the invention, the device also comprises a second lifting platform 5 and a telescopic platform 6; the second lifting platform 5 is arranged on the tower guide rail 1 and can move up and down along the tower guide rail 1, and the second lifting platform 5 is positioned below the first lifting platform 2; the telescopic platform 6 is used for supporting the flow guide sleeve 7, is arranged on the second lifting platform 5, and comprises a base 19, a telescopic piece and a fixed flat plate 22; the base 19 is fixed on the second lifting platform 5 and is sequentially connected with the telescopic piece and the fixed flat plate 22; the fixed flat plate 22 is horizontally arranged and can move vertically or horizontally under the driving of the second lifting platform 5 or the telescopic piece.
In the embodiment of the invention, the guide rod 4 is detachably connected with the flow guide sleeve 7, the guide rod 4 is provided with a guide rod bolt hole 23, the flow guide sleeve 7 is provided with a flow guide sleeve bolt hole 17, and after the guide rod bolt hole 23 is aligned with the flow guide sleeve bolt hole 17, the quartz bolt 8 is simultaneously inserted into the guide rod bolt hole 23 and the flow guide sleeve bolt hole 17 for fixing. The quantity of lifter bolt hole 23 can set up a plurality of as required to the regulation of height, each lifter bolt hole 23 vertical distribution, adjacent lifter bolt hole 23 interval are 40mm, and the internal diameter all is 12 mm. .
In the embodiment of the invention, the loose body 11 is detachably connected to the lower end of the guide rod 4 through a conversion structure, the conversion structure comprises a quartz adapter cylinder 9 and a quartz target rod 10, the quartz adapter cylinder 9 is connected with the lower end of the guide rod 4, the quartz target rod 10 is fixed below the quartz adapter cylinder 9, and the quartz target rod 10 is fixedly connected with the loose body 11; the quartz adapter cylinder 9 is provided with a pin hole, correspondingly, the lower end of the guide rod 4 is provided with a pin hole corresponding to the pin hole, and the quartz adapter cylinder 9 is fixedly connected with the guide rod 4 through the pin hole and the bolt.
In the embodiment of the invention, the bottom of the furnace core pipe 12 is provided with an air inlet, and the top is provided with an air outlet; a first air sealing ring 13 and a second air sealing ring 14 are arranged at the air outlet; the material of the flow guide sleeve 7 is GE-214 high-purity quartz; the fixed flat plate 22 is designed into a circular hollow circular concave step structure with the inner diameter D1, D1 is 240mm, and the material is Teflon; the extensible member is metal telescopic frame 21, be provided with adjust knob 20 on the metal telescopic frame 21 for adjust flexible.
It should be noted that, in the lifting process of the telescopic platform 6, the gaps between the center of the fixed flat plate 22 and the loose body 11 and the sintering female rod 24 are sufficient, and scratch does not occur; in the sintering process, gaps among the guide sleeve base, the tube wall of the furnace core tube 12 and the loose body 11 are sufficient, rubbing cannot occur, and the transparency of the neck region of the loose body is kept good after sintering.
In the embodiment of the invention, the outer diameter of the loose body 11 is 150-200 mm, and the length of the loose body 11 is 1400-1800 mm; the length of the quartz target rod 10 is 500-600 mm; the pipe diameter of the inner wall of the furnace core pipe 12 is 300 mm; the outer diameter of the guide rod 4 is 50 mm; the inner diameters of the first air seal ring 13 and the second air seal ring 14 are both 55mm,
in the embodiment of the invention, as shown in fig. 4, the inner diameter d1:55mm of the upper opening of the flow guide sleeve 7, the outer diameter d2:80mm, the height L3: 80 mm; the inner diameter d3:250mm of the lower opening of the flow guide sleeve 7, the height L4 of the conical surface of the flow guide sleeve 7: 200 mm; height L5 of lower opening of flow sleeve 7: 100mm, flow sleeve 7 wall thickness L6: 5 mm. As shown in fig. 5, four layers of hollow small holes 18 are respectively distributed on the conical surface of the flow guide sleeve 7 in an annular manner, and the aperture of each hollow small hole 18 of the flow guide sleeve is 2 mm; the inner diameter of the bolt hole 17 of the flow guide sleeve is 12 mm; the quartz plug 8 is designed into a cylinder, the length is 140mm, and the outer diameter is 8 mm.
The application method of the sintering device of the loose body of the optical fiber preform rod comprises the following steps:
s1, mounting of the guide rod 4 and the loose body 11:
the second lifting platform 5 and the telescopic piece are controlled to move the fixed flat plate 22 to be right above the furnace core pipe 12, so that the fixed flat plate 22 is supported below the flow guide sleeve 7; the second lifting platform 5 is operated until the distance L1 between the base of the flow guide sleeve 7 and the opening of the furnace core pipe 12; the first lifting platform 2 is controlled to enable the guide rod 4 to extend into the flow guide sleeve 7, and the loose body 11 is fixedly connected to the lower end of the guide rod 4;
s2, mounting the guide rod 4 and the flow guide sleeve 7:
the second lifting platform 5 is controlled, and the height of the telescopic platform 6 is reduced until the distance L2 between the base of the flow guide sleeve 7 and the pipe orifice of the furnace core pipe 12; moving the guide rod 4 until the guide rod bolt hole 23 is aligned with the guide sleeve bolt hole 17, and inserting and fixing the quartz bolt 8 into the guide rod bolt hole 23 and the guide sleeve bolt hole 17 at the same time to fixedly connect the guide rod 4 and the guide sleeve 7; subsequently, the second lifting platform 5 and the telescopic piece are operated to enable the fixed flat plate 22 to be withdrawn from the working area;
s3, feeding the loose body 11 into a sintering area:
the first lifting platform 2 is controlled to enable the guide rod 4 to descend until the bottom of the loose body 11 enters a high-temperature area of the furnace core pipe 12 (namely the top end position of the graphite heater 15), and meanwhile, the first air sealing ring 13 and the second air sealing ring 14 respectively cover the top of the furnace core pipe 12 in sequence;
s4, starting sintering:
firstly, dehydroxylating the loose body 11, raising the temperature in the furnace core pipe 12 to 900-; stopping chlorine gas intake after the dehydroxylation process is finished, and automatically lifting the loose body 11 to the top end of the heater 15; continuously raising the temperature in the furnace core pipe 12 to 1500 ℃, and slowly descending the loose body 11 to perform glass transparentization; stopping helium gas inlet and the guide rod 4 from rotating after the loose body 11 is completely vitrified; the temperature in the furnace core pipe 12 is reduced to 800-;
s5, separation of the guide rod 4 from the flow guide sleeve 7:
after the diversion sleeve 7 is cooled to the room temperature, the second lifting platform 5 and the telescopic piece are regulated and controlled, so that the fixed flat plate 22 moves to the lower part of the diversion sleeve 7 and supports the diversion sleeve 7; pulling the quartz bolt 8 away;
s6, unloading the sintering mother rod 24:
after the guide rod 4 is separated from the guide sleeve 7, the guide rod 4 is controlled to descend, and the sintering mother rod 24 is unloaded;
s7, cleaning the flow guide sleeve 7:
the flow guide sleeve 7 can be used for cleaning surface particle impurities by means of a dust collector.
In the invention, the distance between the bottom of the flow guide sleeve 7 and the pipe orifice of the furnace core pipe 12 is L1: 2000-2300 mm, and L2: 1800-2000 mm.
In the dehydroxylation process of the loose body 11, after chlorine and helium are introduced from the bottom of the furnace core pipe 12, the upper end necking area 25 of the loose body 11 is completely covered by the base of the flow guide sleeve 7, so that the concentration of the chlorine entering the inside of the flow guide sleeve 7 can be ensured, when the necking area 25 of the loose body 11 fully reacts with the chlorine, the generated waste gas, namely hydrogen chloride and the redundant chlorine can be discharged from the hollow small hole 18 of the flow guide sleeve in time, and finally the chlorine is discharged out of the furnace core pipe 12.
Example 1:
s1, electrically controlling and adjusting the second lifting platform, lifting the height of the telescopic platform until the distance between the bottom of the guide sleeve and the pipe orifice of the furnace core pipe is 2100mm, and mounting a loose body with the length of 1400mm and the outer diameter of 200mm on the quartz adapter cylinder by means of a quartz target rod with the length of 550 mm;
s2, electrically controlling and adjusting the second lifting platform, reducing the height of the telescopic platform until the distance between the guide sleeve base and the furnace core tube orifice is 1900mm, and inserting a quartz bolt with the length of 140mm and the outer diameter of 8mm after the guide sleeve bolt hole is aligned with the guide rod bolt hole to realize the fixed connection of the guide rod and the guide sleeve; adjusting the telescopic platform to evacuate the telescopic platform from the operation area;
s3, enabling the bottom of the loose body to enter a high-temperature area of the furnace core pipe at a speed of 200mm/min, namely the top end of the graphite heater, and enabling the first air seal ring and the second air seal ring to respectively cover the top of the furnace core pipe in sequence;
s4, raising the temperature in the furnace core tube to 1050 ℃ at 8.5 ℃/min, starting to lower the loose body to the top end of the graphite heater at the speed of 8mm/min, rotating the guide rod at the speed of 3rpm, and introducing chlorine and helium into the bottom of the synchronous furnace core tube at the flow rates of 1.0slm and 17slm respectively; stopping chlorine gas intake after the dehydroxylation process is finished, and automatically lifting the loose body to the top position of the graphite heater; the furnace core pipe is continuously heated to 1500 ℃ at the temperature of 11.0 ℃/min, the loose body is continuously reduced at the speed of 5mm/min for glass transparentization, and the gas inlet flow of the synchronous helium is 15 slm; stopping helium gas inlet and the guide rod from rotating after the loose body is completely vitrified; reducing the temperature in the furnace core pipe to 900 ℃, and lifting the sintering mother rod out of the furnace core pipe at the speed of 100mm/min until the distance between the base of the guide sleeve and the pipe orifice of the furnace core pipe is 1900 mm;
s5, after the flow guide sleeve is cooled to the room temperature, the second lifting platform and the telescopic piece are adjusted and controlled, so that the fixed flat plate moves to the position below the flow guide sleeve, the flow guide sleeve is supported, and the quartz bolt is pulled away;
s6, continuously electrically controlling and adjusting the lifting device until the distance between the guide sleeve base and the furnace core pipe orifice is 2100mm, and unloading the sintering mother rod;
s7, the dust collector cleans the particle impurities on the surface of the flow guide sleeve.
And after sintering, continuing extending, PK testing, OVD (over voltage) wrapping, optical fiber drawing and optical parameter testing on the transparent sintered mother rod.
Compared with the conventional sintering device and sintering method, as shown in fig. 13, the average value, the range value and the standard deviation of the relative refractive index difference of the axial core cladding of the optical fiber preform are respectively reduced from 0.394%, 0.083% and 0.026% to 0.385%, 0.024% and 0.007%, and the uniformity of the relative refractive index difference of the axial core cladding of the optical fiber preform is improved.
Compared with the traditional sintering device and sintering method, as shown in FIGS. 10 and 11, the average value, the deviation value and the standard deviation of the attenuation coefficient of 1383nm of the optical fiber are respectively reduced from 0.378dB/km, 1.590dB/km and 0.286dB/km to 0.275dB/km, 0.046dB/km and 0.010dB/km, the uniformity of the water peak of the optical fiber is improved, and the quality of the optical fiber is obviously improved.
Compared with the conventional sintering device and sintering method, as shown in fig. 14, the MFD coefficient difference value and standard deviation of the optical fiber 1310nm are respectively reduced from 2.08 μm and 0.41 μm to 0.64 μm and 0.10 μm, the MFD coefficient difference value and standard deviation of the optical fiber 1550nm are respectively reduced from 1.27 μm and 0.30 μm to 0.50 μm and 0.10 μm, the MFD coefficient uniformity of the optical fiber 1310nm and 1550nm is improved, and the optical fiber quality is remarkably improved.
Example 2:
s1, electrically controlling and adjusting a second lifting platform, lifting the height of the telescopic platform until the distance between the bottom of the flow guide sleeve and the pipe orifice of the furnace core pipe is 2200mm, and mounting a loose body with the length of 1600mm and the outer diameter of 180mm on the quartz adapter cylinder by virtue of a quartz target rod with the length of 550 mm;
s2, electrically controlling and adjusting the second lifting platform, reducing the height of the telescopic platform until the distance between the guide sleeve base and the furnace core tube orifice is 1800mm, and inserting a quartz bolt with the length of 140mm and the outer diameter of 8mm after the guide sleeve bolt hole is aligned with the guide rod bolt hole to realize the fixed connection of the guide rod and the guide sleeve; adjusting the telescopic platform to evacuate the telescopic platform from the operation area;
s3, enabling the bottom of the loose body to enter a high-temperature area of the furnace core pipe at a speed of 200mm/min, namely the top end of the graphite heater, and enabling the first air seal ring and the second air seal ring to respectively cover the top of the furnace core pipe in sequence;
s4, raising the temperature in the furnace core tube to 1170 ℃ at the speed of 8.5 ℃/min, starting to lower the loose body to the top end of the graphite heater at the speed of 8mm/min, rotating the guide rod at the speed of 3rpm, and introducing chlorine and helium into the bottom of the synchronous furnace core tube at the flow rates of 0.9slm and 18slm respectively; stopping chlorine gas intake after the dehydroxylation process is finished, and automatically lifting the loose body to the top position of the graphite heater; the furnace core pipe is continuously heated to 1500 ℃ at the temperature of 11.0 ℃/min, the loose body is continuously reduced at the speed of 5mm/min for glass transparentization, and the gas inlet flow of the synchronous helium is 15 slm; stopping helium gas inlet and the guide rod from rotating after the loose body is completely vitrified; reducing the temperature in the furnace core pipe to 900 ℃, and lifting the sintering mother rod out of the furnace core pipe at the speed of 100mm/min until the distance between the base of the guide sleeve and the pipe orifice of the furnace core pipe is 1800 mm;
s5, after the flow guide sleeve is cooled to the room temperature, the second lifting platform and the telescopic piece are adjusted and controlled, so that the fixed flat plate moves to the position below the flow guide sleeve, the flow guide sleeve is supported, and the quartz bolt is pulled away;
s6, continuing to electrically control and adjust the lifting device until the distance between the guide sleeve base and the furnace core pipe orifice is 2200mm, and unloading the sintering mother rod;
s7, the dust collector cleans the particle impurities on the surface of the flow guide sleeve.
And after sintering, continuing extending, PK testing, OVD (over voltage) wrapping, optical fiber drawing and optical parameter testing on the transparent sintered mother rod.
Compared with the conventional sintering device and sintering method, as shown in fig. 13, the average value, the range value and the standard deviation of the relative refractive index difference of the axial core cladding of the optical fiber preform are respectively reduced from 0.394%, 0.083% and 0.026% to 0.374%, 0.020% and 0.005%, and the uniformity of the relative refractive index difference of the axial core cladding of the optical fiber preform is improved.
Compared with the traditional sintering device and sintering method, as shown in fig. 10 and 12, the average value, the deviation value and the standard deviation of the 1383nm attenuation coefficient of the optical fiber are respectively reduced from 0.378dB/km, 1.590dB/km and 0.286dB/km to 0.274dB/km, 0.026dB/km and 0.004dB/km, the uniformity of the 'water peak' of the optical fiber is improved, and the quality of the optical fiber is obviously improved.
Compared with the conventional sintering device and sintering method, as shown in fig. 14, the MFD coefficient difference value and standard deviation of the optical fiber 1310nm are respectively reduced from 2.08 μm and 0.41 μm to 0.57 μm and 0.08 μm, the MFD coefficient difference value and standard deviation of the optical fiber 1550nm are respectively reduced from 1.27 μm and 0.30 μm to 0.60 μm and 0.09 μm, the MFD coefficient uniformity of the optical fiber 1310nm and 1550nm is improved, and the optical fiber quality is remarkably improved.
The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention, it should be noted that, for those skilled in the art, several modifications and decorations without departing from the principle of the present invention should be regarded as the protection scope of the present invention.
Claims (10)
1. A sintering device for loose bodies of optical fiber preforms is characterized by comprising a lifting device, a guide rod (4), a furnace core pipe (12), a flow guide sleeve (7) and a heater (15); the guide rod (4) is connected with the lifting device on one hand and the flow guide sleeve (7) on the other hand, a loose body (11) is arranged below the flow guide sleeve (7), and a neck reducing area (25) of the loose body (11) is completely covered in the flow guide sleeve (7); the furnace core pipe (12) is arranged below the guide rod (4), and a heater (15) is arranged outside the furnace core pipe (12); the lifting device can drive the guide rod (4) and the flow guide sleeve (7) to move up and down, so that the loose body (11) is driven to move up and down, and the process that the loose body (11) enters the furnace core pipe (12) to be sintered and leaves the furnace core pipe (12) after sintering is finished is realized; the flow guide sleeve (7) comprises a conical cylinder (7-1) and a cylindrical base (7-2) which are distributed up and down, and the process gas can be covered in a necking area (25) of the loose body (11) so as to increase the dehydroxylation effect of the necking area (25); the surface of the conical cylinder (7-1) is provided with a plurality of hollowed-out small holes (18) for exhausting.
2. The apparatus for sintering the loose body of the optical fiber preform according to claim 1, wherein the lifting device comprises a vertically arranged tower guide rail (1) and a first lifting platform (2), and the guide rod (4) is connected with the first lifting platform (2); the first lifting platform (2) can move up and down along the tower guide rail (1) so as to drive the guide rod (4) to move up and down.
3. The apparatus for sintering the loose body of the optical fiber preform according to claim 2, wherein the first lifting platform (2) is further provided with a rotating device (3), and the guide rod (4) is connected with the rotating device (3); the guide rod (4) can horizontally rotate under the driving of the rotating device (3).
4. The apparatus for sintering the loose body of the optical fiber preform according to claim 2, further comprising a second lifting platform (5) and a telescopic platform (6);
the second lifting platform (5) is arranged on the tower guide rail (1) and can move up and down along the tower guide rail (1), and the second lifting platform (5) is positioned below the first lifting platform (2);
the telescopic platform (6) is used for supporting the flow guide sleeve (7), is arranged on the second lifting platform (5), and comprises a base (19), a telescopic piece and a fixed flat plate (22); the base (19) is fixed on the second lifting platform (5) and is sequentially connected with the telescopic piece and the fixed flat plate (22); the fixed flat plate (22) is horizontally arranged and can move vertically or horizontally under the driving of the second lifting platform (5) or the telescopic piece.
5. The apparatus for sintering the loose body of the optical fiber preform according to claim 1, wherein the guide rod (4) is detachably connected to the guide sleeve (7), a guide rod pin hole (23) is formed in the guide rod (4), a guide sleeve pin hole (17) is formed in the guide sleeve (7), and after the guide rod pin hole (23) is aligned with the guide sleeve pin hole (17), the guide rod pin hole (23) and the guide sleeve pin hole (17) are fixed by simultaneously inserting a quartz pin (8) into the guide rod pin hole (23).
6. The apparatus for sintering the loose body of the optical fiber preform according to claim 1, wherein the loose body (11) is detachably connected to the lower end of the guide rod (4) through a conversion structure, the conversion structure comprises a quartz adapter cylinder (9) and a quartz target rod (10), the quartz adapter cylinder (9) is connected to the lower end of the guide rod (4), the quartz target rod (10) is fixed below the quartz adapter cylinder (9), and the quartz target rod (10) is fixedly connected to the loose body (11); the quartz adapter cylinder (9) is provided with a pin hole, correspondingly, the lower end of the guide rod (4) is provided with a pin hole corresponding to the pin hole, and the quartz adapter cylinder (9) is fixedly connected with the guide rod (4) through the pin hole and the bolt.
7. The apparatus for sintering the loose body of optical fiber preform according to claim 1, wherein the heater (15) is a graphite heater annularly disposed outside the muffle tube (12); a graphite heat-insulating felt (16) is arranged outside the heater (15) in an annular mode; the bottom of the furnace core pipe (12) is provided with an air inlet, and the top of the furnace core pipe is provided with an air outlet; and a first air seal ring (13) and a second air seal ring (14) are arranged at the air outlet.
8. The apparatus for sintering the loose body of the optical fiber preform according to claim 4, wherein the material of the flow guide sleeve (7) is GE-214 high-purity quartz; the fixed flat plate (22) is made of Teflon; the telescopic piece is a metal telescopic framework (21), and an adjusting knob (20) is arranged on the metal telescopic framework (21) and used for adjusting the telescopic property.
9. The application method of the sintering device for the loose body of the optical fiber preform rod of any one of claims 1 to 10, characterized by comprising the following steps:
s1, mounting of the guide rod (4) and the loose body (11):
the second lifting platform (5) and the telescopic piece are controlled, the fixed flat plate (22) is moved to the position right above the furnace core pipe (12), and the fixed flat plate (22) is supported below the flow guide sleeve (7); controlling the second lifting platform (5) until the distance L1 between the base of the flow guide sleeve (7) and the opening of the furnace core pipe (12); the first lifting platform (2) is controlled to enable the guide rod (4) to extend into the flow guide sleeve (7), and the loose body (11) is fixedly connected to the lower end of the guide rod (4);
s2, mounting the guide rod (4) and the flow guide sleeve (7):
controlling the second lifting platform (5), and reducing the height of the telescopic platform (6) until the distance L2 between the base of the flow guide sleeve (7) and the opening of the furnace core pipe (12); moving the guide rod (4) until the guide rod bolt hole (23) is aligned with the guide sleeve bolt hole (17), and inserting and fixing the quartz bolt (8) into the guide rod bolt hole (23) and the guide sleeve bolt hole (17) simultaneously to realize the fixed connection of the guide rod (4) and the guide sleeve (7); then, the second lifting platform (5) and the telescopic piece are controlled to enable the fixed flat plate (22) to be evacuated from the working area;
s3, feeding the loose body (11) into a sintering zone:
the first lifting platform (2) is controlled to enable the guide rod (4) to descend until the bottom of the loose body (11) enters a high-temperature area of the furnace core pipe (12), and meanwhile, the first air sealing ring (13) and the second air sealing ring (14) respectively cover the top of the furnace core pipe (12) in sequence;
s4, starting sintering:
firstly, dehydroxylating the loose body (11), raising the temperature in the furnace core pipe (12) to 900-; stopping chlorine gas intake after the dehydroxylation process is finished, and automatically lifting the loose body (11) to the top position of the heater (15); the temperature in the furnace core pipe (12) is continuously raised to 1500 ℃, and the loose body (11) slowly descends to carry out glass transparentization; stopping helium gas intake and the guide rod (4) from rotating after the loose body (11) is completely vitrified; the temperature in the furnace core pipe (12) is reduced to 800-;
s5, separating the guide rod (4) from the flow guide sleeve (7):
after the flow guide sleeve (7) is cooled to the room temperature, the second lifting platform (5) and the telescopic piece are regulated and controlled, so that the fixed flat plate (22) moves to the position below the flow guide sleeve (7) and supports the flow guide sleeve (7); pulling off the quartz plug pin (8);
s6 unloading sintering mother bar (24)
After the guide rod (4) is separated from the guide sleeve (7), the guide rod (4) is controlled to descend, and the sintering mother rod (24) is unloaded;
s7, cleaning the guide sleeve (7).
10. The application method of the apparatus for sintering the loose body of the optical fiber preform rod as claimed in claim 11, wherein in the dehydroxylation process of the loose body (11), after chlorine and helium are introduced from the bottom of the furnace core tube (12), the necking zone (25) at the upper end of the loose body (11) is completely covered by the base of the flow guide sleeve (7) so as to ensure the concentration of the chlorine entering the inside of the flow guide sleeve (7), the necking zone (25) of the loose body (11) is fully reacted with the chlorine, and the generated waste gas hydrogen chloride and the excessive chlorine are timely discharged from the hollow small holes (18) of the flow guide sleeve and finally discharged out of the furnace core tube (12).
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| CN112624600A (en) * | 2021-01-12 | 2021-04-09 | 江苏法尔胜光子有限公司 | Sintering furnace exhaust hood for preparing optical fiber preform and online adjusting method of exhaust pressure |
| CN113277716A (en) * | 2021-05-27 | 2021-08-20 | 四川神光石英科技有限公司 | Equipment for producing high-quality synthetic quartz glass |
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